Key switching for electric organ



March 21, 1967 J. R. BRAND ETAL KEY SWITCHING FOR ELECTRIC ORGAN Filed June 21, 1963 Cal/- 3 JBW a m 100T. 0

n i i am United States PatentOfiiice 3,310,522 Patented Mar. 21, 1967 4 3,310,622. KEY SWITCHING FOR ELECTRIC ORGAN. John R. Brand, Northridge, Bradley J. Piunkett, Van Nuys, and James Beverly, Pacoima, Califi, assrgnors, by mesne assignments, to Warwick Electronics Inc., Chicago, IEL, a corporation of Delaware Filed June 21, 1963, Ser. No. 289,595 12 Claims. (Cl. 841.13)

This invention relates to keyboard electric musical instruments and more particularly to circuitry for expressing selected tones from the switch mechanism which is operated in response to depression of the key of the keyboard.

It is an object of this invention to provide an electric musical instrument circuit in which all of the results which are desired to be accomplished upon depression of a key of the keyboard may be obtained with a single contact switch.

It is another object of this invention to provide simplified circuitry in which a minimum number of key switch contacts are used, thereby minimizing the construction costs and service problems attendant upon multiple switch contacts.

It is a further object of this invention to provide an organ keying circuit in which a minimum number of key contacts are required, specifically in which only one contact is required for each diiierent key of the keyboard, and in which one of the two terminals of each single contact switch may be connected to a common buss, whereby a simplified structure may be effected. Such a simplified structure may, for example, consist of a single, bare conductor or buss, along which are lined the single poles of the single contact key switches, contact being made simply by moving the individual poles into contact with the single buss or conductor. g

It is a further object of this invention to provide an organ in which depression of a key closes a single contact and thereby effects a continuing signal or activating voltage which persists at least as long as the key is held depressed and also serves to stimulate a transient response which may be used to activate transient functions, such as percussion, or other functions which do not persist uniformly co-extensively with the depressed condition of the key. Such a function could be a delayed or gradual buildup of vibrato, or the sustaining of a tone after the key is released.

In accordance with these and other objects which will become apparent hereinafter, a preferred form of the present invention will now be described with reference to the accompanying drawing, wherein FIG. 1 is a block diagram illustrating the functioning of the present invention.

FIG. 2 is a schematic diagram of a portion of the system shown at 2 in FIG. 1.

FIG. 3 is a schematic diagram of circuitry embodied in the block 3 of FIG. 1, and

FIG. 4 is a schematic diagram of the circuitry embodied in block 4 of the system shown in FIG. 1.

Referring to the drawing, the organ system illustrated in FIG. 1 includes a keyboard 11 having a plurality of keys 12. Each key operate a corresponding single contact switch represented by the switch 13 in the bank of switches indicated by the numeral 2.

In accordance with the present invention the closing of the single contact represented by the single pole switch 13 produces two independently useful functions. First, the closing of the single contact 13 serves to apply a sustained or continuing activation of the tone from the corresponding tonesource or generator 14 to the output circuit of the organ shown generally at 16. For this purpose there is one single contact switch 13 for each of the tone generators 14, respectively, and a corresponding conductor or buss 17 for each such switch and tone generator. In the illustration of FIG. 1, the organ is assumed to be of the type in which the tone source 14 is continually operating, but its tOnesignal is not pplied to the output circuit 16 of the organ except when an interposed keying circuit 18 is properly biased or activated from the conductor 17 by the closure of the switch 13. The keying circuit or keyer 18 may, if desired, be of the type illustrated in co-pending application Ser. No. 293,924 filed July 5, 1963 in the name of Floyd A. Cordry.

Although a keyer 18 has been shown, it will be recognized by those skilled in the art that a tone generating 0-scillat-or may be substituted for the combination of the source 14 and keyer 18, the oscillator being normally in a non-oscillating state and oscillating when appropriate voltage appears on conductor 17 s It will also be recognized that in either the keyer 18 or oscillator configuration, a capacitor may be connected to conductor 17 to provide a sustain eifect after the key is opened, as it gradually discharges into the keyer or os cillator load.

Tone signals passed by the keyer 18 into the organ output circuit 16 are illustrated in FIG. 1 as passing through a percussive modulator 19 and thence through an amplifier 21 to a loudspeaker, tone cabinet, or other electro-acoustic transducer 22. It will be readily understood that in an actual organ various other embellishments, such as, voicing 'formants, couplers, and similar modifying circuitry are usually employed.

In accordance with the present invention, the closing of a single contact switch 13 also effects operation of a modifying means, which transiently modifies in some fashion the characteristic of the tone signal. In FIG. 1, there are illustrated, by way of example, two independent and, if desired, concurrently operating, such modifying means. One of these modifying means develops a percussive envelope in the percussion modulator 19 by virtue of a pulse applied through the channel or conductor 23, while the other develops a delay vibrato envelope which is applied from a vibrato modulator 34 through the channel 26 to the several tone sources 14.

These two modifying means are actuated by a pulser, or pulse sensor 3, which senses the closing of any of the switches 13, irrespective of whether or not one or more other switches 13 may previously have been closed and remained closed. Upon each such sensing of a witch closure, the sensor circuit 3 delivers an output pulse shown symbolically at 27.

The pulse 27 is applied to two different, transient, moditying systems. One of these systems is a percussion sys tem, consisting of a coupling circuit 4 which feeds to a monostable multivibrator 28, the output of which is applied through the conductor 23 to the modulator 19, where it serves to amplitude-modulate the tone signal passing through the organ output circuit to the speaker 22. The multivibrator 28 may, if desired, be made free-running by switching the double throw switch shown symbolically at 29, causing the multivibrator to feed back through a suitable circuit 31, and thus run as a free-running oscillator. In this case, continuous repetitive pulses are applied to the modulator 19, independent of any pulse signals generated in response to closing of a key switch 13. In similar vein, the operation of the percussion portion of the circuit of the organ may be modified by a bypass switch, shown symbolically at 32, which causes tone signals to bypass the modulator, and thus energize the speaker 22 in continuous or sustained fashion and without percussion.

The general operation of percussive modulation in an organ as briefly described above is described in detail in Patents Nos. 3,255,294 and 3,235,650.

There may be also or alternatively incorporated into the system a sustain or holdover of the tone after release of the key 12. An example of such a sustain is to be found in said co-pending application Ser. No. 293,924.

The other and independent modifying means which employs the output pulse 27 is a delayed vibrato system, consisting of a pulse shaper 33, the output of which is applied to a modulator 34, that serves to apply an amplitude modulated envelope to the output of the vibrato oscillater 24. The vibrato oscillations delivered through the modulator 34 are then applied through the channel 26 to frequency-modulate each of the tone sources 14. Such a delayed vibrato system may be of the form described in detail in co-pending application Ser. No. 288,270 filed June 17, 1963 in the names of John R. Brand and Bradley J. Plunkett.

Details of the keying circuit 2 are illustrated in the schematic diagram FIG. 2, wherein each of the single contact switches 13 has one of its terminals connected to a common conductor or bus 36, which is in turn connected to the terminal 37 leading to the aforementioned pulser 3.

The other terminal 38 of each single contact switch 13 is connected through a resistor 39 and thence through a capacitor 41 to a common or ground connection. Also from the terminal 38 is taken the connection 17 going to the particular keyer 18 corresponding to the associated key switch 13. When a given switch 13 is open, its terminal 38 is maintained at a given negative potential by a negative potential source 49 connected to the terminal 38 through a resistor 42.

The common bus 36 is connected through the conductor 37 to the pulser or sensing circuit shown in FIG. 3. This circuit includes a transistor 43, the collector of which is connected to the output terminal 44 of the pulser 3 and also to a resistor 46, the other end of which is connected to a source of positive potential shown at 47. The emitter of the transistor 43 is connected to the terminal 37. Between the emitter and base of the transistor 43 is connected a network 48 consisting of resistors 49, 50, and 55, and capacitor 51, which serves to enhance conduction of the transistor 43, as will be described hereinafter.

The resistors 52 and 53 constitute a voltage divider between the voltage source 47 and ground, to provide a point 54 of intermediate voltage which is connected to network 48.

Resistors 52 and 49 are low in value compared to resistors 46 ,49, and 50.

By referring to FIGS. 2 and 3 it will be seen that whenever a switch 13 is closed, the positive potential from the terminal 47 will be applied through the resistors 52 and 49 to the output conductor 17. This potential will serve to actuate the keyer 18 and permit tones from the corresponding tone signal source 14 to pass into the output circuit 16 of the organ. Potential will remain on the line 17 as long as the switch 13 remains closed, i.e., as long as the corresponding key 12 is held down, and this will keep the keyer 18 conducting and permit continuous passage of tone signals from the source 14.

At the moment of closing the switch 13, a second phenomenon takes place, which is employed by the modifying circuitry and systems mentioned hereinbefore. The appearance of positive potential on the terminal 38 serves to send a surge of charging current into the capacitor 41. This charging current is sensed by the transistor 43, by virtue of the resulting voltage drop across resistor 49 and causes a momentary drop in potential on the terminal 44 as shown at 27. A predetermined and brief time after closing of a given switch 13 the charging current will have dropped to a point where the voltage drop across resistor 49 is insufficient to hold the transistor 43 conducting, and the voltage on the collector of transistor 43 will then return to its quiescent or steady state value, thus terminating the pulse 27. The charge developing on the differentiating capacitor 51 after closing switch 13 serves to accelerate the conduction of the transistor 43, and hence steepens the leading edge of the output pulse 27.

The output pulse 27 appearing on the terminal 44 is used to trigger the transient effects described hereinbefore.

The circuit of FIG. 4 serves to remove the effect of varying DC. or quiescent potentials on the terminal 44 resulting from the continued closing of a variable number of key switches 13, and also insures that only negative going pulses are transmitted to multivibrator 28 through switch 29.

It is to be understood that the percussion modulator and vibrato modulator are but two examples of transient systems which may employ the pulse 27. It will be readily understood that the output from vibrato modulator 34 may, if desired, be either used simultaneously or alternatively as a tremolo signal to introduce tremolo instead of, or in addition to, vibrato, into the tone sources 14, or to another tone signal modulator somewhere in the signal channel. For example, the tremolo signal could be applied to modulator 19.

While the instant invention has been shown and described herein in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention which is therefore not to be limited to the details disclosed herein, but is to be afforded the full scope of the following claims.

What is claimed is:

1. In an electric musical instrument having a keyboard including a plurality of keys, a corresponding plurality of single contact switches actuated by the respective keys, a plurality of electric tone signal sources, an output circuit including an electro acoustic transducer for translating tone signals from said sources into audible signals, the combination of:

means responsive to each actuation of a said switch for delivering a single electric pulse, irrespective of the position of any other switch,

modifying means responsive to said pulse for transiently modifying the characteristics of said tone signals, and

means responsive to said actuation for applying tone signals to said organ output circuit for as long as the ,key corresponding to a tone is in actuated position.

2. The combination of claim 1 including a common buss, one terminal of each of said switches being connected to said buss, and circuit means for connecting said buss to a potential source.

3. In an electrical musical instrument having a keyboard including a plurality of keys, a corresponding plurality of single contact switches actuated by the respective keys, a plurality of electric tone signal sources, an output circuit including an electro acoustic transducer for translating tone signals from said sources into audible signals, the combination of:

means responsive to each actuation of a switch for delivering a single electric pulse;

one shot multi-vibrator means for delivering a modulating pulse in response to actuation by said single electric pulse;

modulating means in said output circuit for amplitude modulating said tone signals in response to said modulating pulse delivered by said multi-vibrator means; and

means responsive to said actuation of a said switch for applying tone signals to said output circuit for as long as the key corresponding to a tone is in actuated position,

whereby upon each actuation of a key, irrespective of the position of any other key, a percussive, amplitude-modulating pulse is applied to said modulating means, thereby to pass a percussive burst of tone to said transducer.

4. The combination of claim 3 wherein said modifying means comprises:

a vibrato oscillator for frequency-modulating said tone signal sources, and

means responsive to said electric pulse for transiently modifying the output amplitude of said vibrato oscillator applied to said signal sources.

5. In an electrical musical instrument having a keyboard including a plurality of keys, a corresponding plurality of single contact switches actuated by the respective keys, a plurality of electric tone signal sources, an output circuit including an electric acoustic transducer for translating tone signals from said sources into audible signals, the combination of:

means responsive to each actuation of a switch for delivering a single electric pulse;

a vibrato oscillator for modulating said tone signal sources;

means responsive to said electric pulse for transiently modifying the output amplitude of said vibrato oscillator applied to said signal sources; and

means responsive to said actuation of a said key switch for applying tone signals to said organ output circuit for so long as the key corresponding to a tone is in actuated position. i 6. In an electrical musical instrument having a keyboard including a plurality of keys, a corresponding plurality of single contact switches actuated by the respective keys, a plurality of electric tone signal sources, an output circuit including an electro acoustic transducer for translating tone signals from said sources into audible signals, the combination of:

a capacitor associated with each said switch; means for changing the voltage on said capacitor in response to actuation of its corresponding switch,

means for sensing the transient change in charge on each capacitor resulting from said voltage change and for responding thereto with delivery of an electric pulse,

modifying means responsive to said electric pulse for transiently modifying the characteristics of said tone signals and,

means responsive to said actuation for applying tone signals to said output circuit for as long as the key corresponding to a tone is in actuated position.

7. The combination of claim 6 wherein said sensing means includes a transistor, each said capacitor being connected in series with its corresponding switch and all of said series connected switches-capacitors being connected to a source of voltage through circuit means including said transistor, and

network means connected to said transistor for eifecting rapid change of the collector current of said transistor during change in charge on each said capacitor.

8. The combination of claim 6 wherein said sensing means is a three-electrode device.

9. The combination of claim 8 wherein said device is a transistor.

10. Apparatus for activating simultaneously a continuous and a transient musical effect upon depression of an electrical musical instrument keyboard key, comprising:

tone generator activating means;

means for applying an activating voltage to said tone generator activating means to pass a tone for so long as a key is held depressed;

means for sensing a transient flow of current resulting from application of said voltage; and

means for activating said transient musical effect in response to said sensing of said transient flow.

11. Apparatus in accordance with claim 10 wherein said sensing means is effective to sense a transient flow of current in said tone generator activating means.

12. Apparatus in accordance with claim 10 wherein said applying means efiects a transient flow of current derived from said activating voltage whenever a said key is depressed, irrespective of the position of any other key in the keyboard.

References Cited by the Examiner UNITED STATES PATENTS 3,039,347 6/1962 Krauss et al 84l.13 X

ARTHUR GAUSS, Primary Examiner.

D. D. FORRER, Assistant Examiner. 

3. IN AN ELECTRICAL MUSICAL INSTRUMENT HAVING A KEYBOARD INCLUDING A PLURALITY OF KEYS, A CORRESPONDING PLURALITY OF SINGLE CONTACT SWITCHES ACTUATED BY THE RESPECTIVE KEYS, A PLURALITY OF ELECTRIC TONE SIGNAL SOURCES, AN OUTPUT CIRCUIT INCLUDING AN ELECTRO ACOUSTIC TRANSDUCER FOR TRANSLATING TONE SIGNALS FROM SAID SOURCES INTO AUDIBLE SIGNALS, THE COMBINATION OF: MEANS RESPONSIVE TO EACH ACTUATION OF A SWITCH FOR DELIVERING A SINGLE ELECTRIC PULSE; ONE SHOT MULTI-VIBRATOR MOEANS FOR DELIVERING A MODULATING PULSE IN RESPONSE TO ACTUATION BY SAID SINGLE ELECTRIC PULSE; MODULATING MEANS IN SAID OUTPUT CIRCUIT FOR AMPLITUDE MODULATING SAID TONE SIGNALS IN RESPONSE TO SAID MODULATING PULSE DELIVERED BY SAID MULTI-VIBRATOR MEANS; AND MEANS RESPONSIVE TO SAID ACTUATION OF SAID SWITCH FOR APPLYING TONE SIGNALS TO SAID OUTPUT CIRCUIT FOR AS LONG AS THE KEY CORRESPONDING TO A TONE IS IN ACTUATED POSITION, 